ABSTRACT
Fifty oocytes were studied with light microscope and electron microscope. The shape of oocyte is round, about 50—100?m in diameter. The nucleus is large and spheroidal in shape. The diameter of the nucleus is 15—20?m. All the oocytes are surrounded by zona pellucida and follicular cells. Call-Exner bodies are seen between these follicular cells. A great number of microvilli are present on the surface of oocytes. The paired membranes of nucleus envelope is clearly seen. There are a lot of nuclear pores on nuclear envelope, about 4,000/mm~2. The nuclear pore complex is disinct. The cytoplasm of oocyte abounds with organelles which are distributed regularly. The cristae of mitochondria are short and scarety. The mitochondrial matrix becomes very dense. The cavities of endoplasmic reticulum are distended. Well developed Golgi complex are usually found at the periphery of oocytes. Annulate lamellae consist of parallel flat sacs with a length of 1.5—2.0?m. There are structures like nuclear pores on the flat sac. Some bunchs of fibrous material in the cytoplasm of oocytes are called yolk plates Each yolk plate consists of a regular alternating dark and light bands with a periodicity of 20nm. Cortical granules are round with a diameter of 0.2—0.4?m. They are wrapped up in a membrane. Their electron density is high.